ML20046A032

Special Rept:On 930704,TS Time Limit Expired for SGTS Exhaust Stack High Range Radioactivity Monitor Declared Inoperable on 930701 Due to Low Sample Flow Reading. Suspected Degraded Pump Replaced.Followup Will Be Provided

ML20046A032
Person / Time
Site:	Clinton
Issue date:	07/19/1993
From:	Phares R ILLINOIS POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
U-602155, NUDOCS 9307230364
Download: ML20046A032 (2)

Text

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LJ-602155

9

,, L30-93(07-19)LP IE.100c

,, nrus Power Cornpany

, Chnton Power Staten P.O. Box 678 Chnfon, IL 61727 ,

July 19,1993 Tel 217 935-8881  !

BLLINOIS PbWER i

Docket No. 50-461 1

Document Control Desk j Nuclear Regulatory Commission l Washington, D.C. 20555

]

l

Subject:

Special Report: Extended Inoperability of the SGTS Exhaust Stack High Range l Badioactivity Monitor (ORIX-PR008) at Clinton Power Station (CPS) I

Dear Sir:

Clinton Power Station (CPS) Technical Specification 3.3.7.5, " Accident Monitoring l Instrumentation," requires the Standby Gas Treatment System (SGTS) Exhaust High Range j Radioactivity Monitor to be OPERABLE when the plant is in OPERATIONAL CONDITION 1,2, or 3. In the event the monitor becomes inoperable, the Technical Specification requires (per Action Statement 81) either the monitor be restored to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or a preplanned alternate method of monitoring the parameter be initiated and a Special Report be submitted to the Commission pursuant to Technical Specification 6.9.2 within 14 days. The Special Report must outline the action tak.en, the cause of the inoperability, and plans and schedule for restoring the monitor to OPERABLE status.

At 2100 hours0.0243 days <br />0.583 hours <br />0.00347 weeks <br />7.9905e-4 months <br /> on July 4,1993, the SGTS Exhaust Stack High Range Radioactivity Monitor (0RIX-PR008) had been inoperable for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. As a result, this special report is being submitted in accordance with the CPS Technical Specifications.

l Event Summarv (Desc!iption and Cause)

! At 2100 hours0.0243 days <br />0.583 hours <br />0.00347 weeks <br />7.9905e-4 months <br /> on July 1,1993, ORIX-PR008 was declared inoperable due to a low sample I

flow reading while performing a required surveillance on the monitor. Maintenance Work Request (MWR) D52149 was initiated to troubleshoot and identify the cause of the out-of-specification flow reading. A degraded pump was suspected to be the cause of the inoperability.

Subsequently, a new replacement pump was installed but failed to produce an adequate system

~

flow. A second replacement pump was installed, but again, the replacement pump failed to produce adequate system flow. Additional troubleshooting was therefore performed on the inoperable system.

During the ongoing troubleshooting, the 72-hour Technical Specification time limit expired at 2l00 hours on July 4,1993. CPS initiated the pre-planned alternate. method of monitoring the SGTS exhaust radiation level as required by Action Statement 81 of the CPS Technical Specification Table 3.3.6.5-1. These alternate methods are described in Section 8.7 of I b CPS Procedure 7410.77, " Operation of Eberline Accident Range Monitors (AXMs)." .

9307230364 930719 7M PDR ADOCK 05000461 S PDR f

t q' N Page 2 of 2 to U-602155 Results from the continuing troubleshooting were inconclusive. The system was disassernbled, visually inspected, and cleaned. As no discernible flow restrictions within the system were found, the focus of the inoperability returned to the pump. A third pump from stock was installed into the system. This pump produced a flow rate which was within the required flow limits. Post-maintenance testing was performed and was completed successfully in accordance with CPS Procedures 9437.64,7410.75 and 6948.01. The monitor was then restored to OPERABLE status at 0610 hours0.00706 days <br />0.169 hours <br />0.00101 weeks <br />2.32105e-4 months <br /> on July 10,1993.

IP is now performing a thorough review to determine why adequate system flow could not be achieved with the first and second replacement pumps. The cause of the initial in-service pump failure degradation (which initially caused the monitor to be declared inoperable) is also being investigated. IP is currently working with Eberline (the system vendor) and Metal Bellows (the pump supplier) as part of this efrort. The results ofIP's investigation will be provided in a follow-up letter to the NRC to be submitted by September 3,1993.

Sincerely yours, N RMw Richard F. Phares Director- Licensing CLJE/nis cc: NRC Clinton Licensing Project Manager NRC Resident Office, V-690 Regional Administrator, Region III, USNRC lilinois Department of Nuclear Safety